Many water-based polymer systems for water-based inks and overprint varnishes are readily coatable onto paper, plastic or metal substrates.
Such polymeric systems are disclosed in the following patents:
U.S. Pat. No. 4,946,932 assigned to Eastman Kodak Company discloses water-dispersible polyester and polyesteramide blends with certain vinyl polymers. The products are obtained via semi-batch emulsion polymerization of one or more vinyl monomers in the presence of an aqueous dispersion of a preformed water-dispersible polyester or polyesteramide. The product is a milky latex dispersion having particle sizes in the range of about 150 nm to about 500 nm.
U.S. Pat. No. 4,939,233 assigned to Eastman Kodak Company discloses an aqueous dispersion comprising a water-dispersible polyester or polyesteramide and a vinyl polymer having a majority of repeat units from vinyl acetate wherein the latex polymer is formed via emulsion polymerization of the vinyl monomer in the presence of an aqueous dispersion of the polyester or polyesteramide. However, some of these polymeric materials retain an undesirable water sensitivity when the coatings are dried. This water sensitivity can result in blocking or transfer of color if the wet surface comes in contact with another substrate. Such sensitivity can also result in total removal of the ink film from nonporous substrates such as plastic film or metal foil. Thus, it is desirable to have water-dispersible polymeric compositions which exhibit excellent dry- and wet-block resistance in overprint varnish applications and/or excellent water-resistance, adhesion and printability in ink applications.